Your Spectrum
Issue 10, December 1984 - Letters Page
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ISSUE FORTH

I was interested to read in the September issue of YS an article about the '64K Spectrum' by Simon Goodwin. Two weeks prior to reading the article I had to return my 48K Spectrum to Sinclair Research for repair (for the fifth time since 1982). I have just received my 'repaired' Spectrum back and it's actually a brand new machine.
Naturally, my first action was to take the back off the machine to find out whether or not it was one of the 64K Issue 3.5 models; it is in fact an Issue 4a model and the circuit board is completely different to my previous Issue 2 Spectrum. I don't know how different my Issue 4a Spectrum is from an Issue 3 Mk 5 (or any other Issue 3), as I've never had the opportunity to look inside an Issue 3. Perhaps you could publish a sketch of the inside of an Issue 3 machine to enlighten me?
Andy Sheppard, Burnley, Lancs

We haven't yet managed to get our hands on one of the new Mk 5s - so it's going to be difficult to provide you with a sneak look at the said device. However, if you want a rough idea of what goes on in an Issue 3, try looking at Sexing Your Spectrum, an article we published in the third issue of YS (where else?). If you haven't got a copy, see if you can look in a friend's as I have a rather nasty feeling it's getting rather rare. Ed.
 

SHORT SHRIFT

I am writing to you because, as a devoted follower of the Sinclair cult, I went out and bought myself a copy of your highly esteemed mag. Having read this from front to back, I sent off for some back issues (1, 3 and 4) but received only 1 and 4 with a note saying that all issues of number 3 were sold out - but I would, however, receive a copy of issue 9 for my anguish. So I sat down and read the issues I now had, but soon begin to pine for my non- existent issue 3. Also to my further grief (and being a moron of the highest order) I don't understand a word (or digit??) of machine code; I therefore welcomed Paper Data in issue 2. But wait, yet another aid to my gradual mental demise ... no addresses were given as to the purchase of the aforementioned books. Also, being a great lazy wally, I 		F O R U M

Is there something you're not telling us? From next issue on, there'll be a crisp tenner awarded to the Star Letter of the Month. Don't miss out ... write to Forum, Your Spectrum, 14 Rathbone Place, London W1P 1DE. 		However, having said that, there is one problem that I keep stumbling over in some of your articles ... the quotation of addresses in Hex, without a decimal equivalent given!?
Now taking a purely logical standpoint to the above problem, I have come up with the following five possible solutions to this crisis situation:
1) Threaten the writers with Barry Manilow (audio or visual) if they refuse to mend the error of their ways.
2) Make me buy a Hex-Dec converter (sorry, I'm too tight- fisted to do it myself).
3) Publish a Hex-Dec converter. for Hex up to at least DEC 65535 (beg, beg).
4) Threaten the writers with Barry Manilow and Des O'Connor (audio and visual!) if they refuse to co-operate.
5) Shoot myself!
Anthony Mayers, Wrexham, Clwyd

Aaargh ... anything but Bazza and Des! Well, we'll work on option 4, but if you can't wait that long try option 5. Ed.
 

DUMPS ON A SHOESTRING

Looking through my back issues of YS, I couldn't help feeling envious at the number of conversions of Andrew Pennell's Dumps of Distinction program. Wouldn't it be great to have screen dumps all over my bedroom wall? All I need is a printer costing around £300! Hah!
Gazing around my room, my eyes alighted on my obsolete ZX Printer. Is it possible, I asked myself. After a few hour's work (honest!), I'd converted the program to work on my little machine. Out came the scissors and Sellotape and I'd managed the impossible (Dramatic stuff this! Ed.). The trimmer listing fits nicely on to an A4 sheet - glue might be better than tape to affix it, but be careful or you'll end up with nasty blotches all over the place.
The result is about the same size as Mr Pennell's dumps - but not quite as pretty. But if you've only got a ZX Printer and your piggy-bank's not full to bursting, what else can you do? I leave the task of pushing the ZX Printer to further limits to all the thousands of you out there who own one - come on you lot, there's nothing to be ashamed of in owning a ZX Printer you know.
David Valentine, Mansfield

On the next page is David Valentine's re-working of Dumps of Distinction for the ZX Printer.
have an (original) copy of The Quill but would also like some advice on the available arcade games designers. So would you please, please, please advise me on how to:
a) Reserve myself a copy of the much sought after YS issue 3.
b) Order a copy of Spectrum Machine Language For The Absolute Beginner.
c) Obtain a copy of a good arcade games designer.
Philip Hankinson, Warrington

a) Hah!, no chance!; b) walk into Smith's.; c) see (b). Troubleshootin 'Pete.
 

DRAG AT YS?

Hello from one of the Your Spectrum fans. Fine magazine, excellent reading, guaranteed to produce the bags under the eyes and the twitchy finger syndrome so distinctive of the Spectrum addict. Well done! ('And so you ought to be' says my Dad when he's trying to get me to bed.)
While I'm on the subject of my Dad, he's part of the problem I'm writing to you about. He uses a BBC-based system. Ouch, I'm sorry, I didn't really say that word. I've told him loads of times but he's just plain arrogant. His system uses a Microvitec 1451 monitor which I'd like to use with the Spectrum. I'm one of your original fans and have a complete set of YS (wow?), so I dug out issue 2 and read Ian Beardsmore's article on doing the necessary surgery. Everything Spectrumwise is in order (Issue 3 and outside guarantee period, etc).
My problem is whether the composite video signal produced by Ian's Spectrum mods will drive the Microvitec monitor which has RGB input. If the answer is "no, Ian's method won't work", is there any other way to connect the two items? Some sort of interface perhaps? Do you know of any manufacturer who may produce a kit or whatever, to carry out this conversion?
Finally, a much more 		important question - a question which has been at the heart of many a finger-resting coffee break since the amazing Issue 1 first hooked us. Who is she, the lady on the cover? She with the green necklace and blue eyes. What is she thinking as she pensively studies the lighting system? Is this Toni Baker, Sue Denham or perhaps Penny Page? After much debate, my friends and I think we know. Fingering a scalpel with such longing ... dreaming of hacking the then soon- to- be- released Jet Set Willy ... it must be, please tell us we're right - Andrew Pennell in drag?
Mark Quilliam, Gunnislake, Cornwall

Taking your minor question first, no Ian's method won't work with the Microvitec. But if you get hold of Adapt on 01- 504 2840, they'll send you an excellent RGB interface for £29.95 which does make the Speccy produce pretty pictures. As for your second and, as you say, more important question, sorry to disappoint you but Andy didn't look good enough in drag to grace our front cover. However, that's him on the front of issue 8, so don't annoy him too much or it'll be BIG trouble! Just for you, here's a photo of Andy Pennell, hacker extraordinaire ... 'orrible, isn't it? Ed. Andy Pennell picture
 

A HEXING QUESTION

First of all, having bought your mag since issue 1, may I take this opportunity to congratulate you on a publication which is nothing short of excellent. 

7EC2       ORG  32450
 
 
5B00 PRBUF EQU  23296
Saves the stack pointer (SP) in case the Break key is pressed. 
 
 
7EC2 START LD   (BOT),SP
Defines DE to be the next block of code to be printed. 
7EC6       LD   DE,48981
7EC9       CALL SECT
7ECC       LD   DE,27221
7ECF       CALL SECT
7ED2       LD   DE,5398
7ED5       CALL SECT
7ED8       RET
Prints out one section of the screen. 
7ED9 SECT  LD   C,0
7EDB SECT1 CALL LINE
7EDE       INC  C
7EDF       LD   A,C
7EE0       CP   0
7EE2       JR   NZ,SECT1
7EE4       CALL PRINT
7EE7       RET
Prints out one vertical line of a section. 
7EE8 LINE  PUSH BC
7EE9       PUSH DE
7EEA       XOR  A
7EEB       LD   (BUFFX),A
7EEE       LD   B,D
7EEF NXY   PUSH DE
7EF0       PUSH BC
7EF1       CALL POINT
7EF4       LD   B,A
7EF5       INC  B
7EF6       LD   A,1
7EF8 NXY1  RRCA
7EF9       DJNZ NXY1
7EFB       AND  (HL)
7EFC       PUSH AF
7EFD       LD   A,H
7EFE       RRCA
7EFF       RRCA
7F00       RRCA
7F01       AND  3
7F03       OR   88
7F05       LD   H,A
7F06       LD   B,(HL)
7F07       POP  AF
7F08       LD   A,B
7F09       JR   NZ,INK
7F0B PAPER RRCA
7F0C       RRCA
7F0D       RRCA
7F0E INK   AND  7
7F10       LD   HL,TABLE
7F13       ADD  A
7F14       ADD  A
7F15       LD   E,A
7F16       LD   D,0
7F18       ADD  HL,DE
7F19       LD   B,3
7F1B NXY2  LD   A,(HL)
7F1C       CALL STORE
7F1F       INC  HL
7F20       DJNZ NXY2
7F22       LD   A,(BUFFX)
7F25       ADD  3
7F27       LD   (BUFFX),A
7F2A       POP  BC
7F2B       POP  DE
7F2C       DEC  B
7F2D       DEC  E
7F2E       JR   NZ,NXY
7F30       CALL PRINT
7F33       POP  DE
7F34       POP  BC
7F35       CALL CKBRK
7F38       RET
Stores a three-by-three character in the area of the printer buffer determined by BUFFX. 
7F39 STORE PUSH BC
7F3A       PUSH HL
7F3B       LD   C,A
7F3C       LD   A,4
7F3E       SUB  B
7F3F       LD   B,A
7F40       LD   HL,PRBUF-32
7F43       LD   DE,32
7F46 STOR1 ADD  HL,DE
7F47       DJNZ STOR1
7F49       LD   A,(BUFFX)
7F4C       LD   B,3
7F4E STOR2 RL   C
7F50       CALL C,PLOT
7F53       INC  A
7F54       DJNZ STOR2
7F56       POP  HL
7F57       POP  BC
7F58       RET
Sets the area containing the three-by-three character in BUFFX. 
7559 PLOT  PUSH AF
7F5A       PUSH BC
7F5B       PUSH HL
  
7F5C       LD   C,A
7F5D       AND  248
7F5F       SRL  A
7F61       SRL  A
7F63       SRL  A
7F65       LD   E,A
7F66       LD   D,0
7F68       ADD  HL,DE
7F69       LD   A,C
7F6A       AND  7
7F6C       LD   B,A
7F6D       INC  B
7F6E       LD   A,1
7F70 PLOT1 RRCA
7F71       DJNZ PLOT1
7F73       OR   (HL)
7F74       LD   (HL),A
7F75       POP  HL
7F76       POP  BC
7F77       POP  AF
7F78       RET
Prints out the first three lines of the printer buffer, and then clears them. 
7F79 PRINT DI
7F7A       PUSH BC
7F7B       PUSH HL
7F7C       LD   HL,PRBUF
7F7F       LD   B,3
7F81 PRIN1 PUSH BC
7F82       CALL 3828
7F85       POP  BC
7F86       DJNZ PRIN1
7F88       LD   A,4
7F8A       OUT  (251),A
7F8C       LD   HL,PRBUF
7F8F       LD   DE,PRBUF+1
7F92       LD   BC,96
7F95       LD   (HL),0
7F97       LDIR
7F99       POP  HL
7F9A       POP  BC
7F9B       EI
7F9C       RET
This is a full screen point; that is it includes the bottom two lines. Thus Y=0 is the top of the screen and Y=191 is the bottom. This routine also returns the address of pixel B=Y, C=X in HL, and the BIT number in A. 
7F9D POINT LD   H,64
7F9F       LD   A,B
7FA0       AND  192
7FA2       SRL  A
7FA4       SRL  A
7FA6       SRL  A
7FA8       ADD  H
7FA9       LD   H,A
7FAA       LD   A,B
7FAB       AND  56
7FAD       SLA  A
7FAF       SLA  A
7FB1       LD   L,A
7FB2       LD   A,B
7FB3       AND  7
7FB5       ADD  H
7FB6       LD   H,A
7FB7       LD   A,C
7FB8       AND  248
7FBA       SRL  A
7FBC       SRL  A
7FBE       SRL  A
7FC0       ADD  L
7FC1       LD   L,A
7FC2       LD   A,C
7FC3       AND  7
7FC5       RET
Scans the Space key and returns to Basic if it's pressed. 
7FC6 CKBRK PUSH AF
7FC7       PUSH BC
7FC8       LD   BC,32766
7FCB       IN   A,(C)
7FCD       RRCA
7FCE       JR   NC,BRK
7FD0       POP  BC
7FD1       POP  AF
7FD2       RET
Puts SP back to its old value, thus effectively clearing the stack. 
7FD3 BRK   LD   SP,(BOT)
7FD7       RET
 
7FD8 BUFFX DEFB 0
7FD9 BOT   DEFB 0
 
7FDB TABLE DEFB 224,224,
                244,0
7FDF       DEFB 192,96,
                192,0
7FE3       DEFB 160,64,
                160,0
7FE7       DEFB 32,64,
                128,0
7FEB       DEFB 96,0,
                96,0
7FEF       DEFB 64,0,
                64,0
7FF3       DEFB 0,64,0,0
 
7FF7       DEFB 0,0,0,0
A disassembled listing of David Valentine's re-working of Andrew Pennell's Dumps of Distinction on to the ZX Printer. You see, pigs can be made to fly!

 

ZIPPING ON A PENSION

At last, somewhat belatedly, I've got Simon Goodwin's Zip Compiler to work - four months after typing in the Zip Library. So why, you may ask did it take me so long? Partly it was my dim eyesight and dimmer wits (well, I am in my early 70s) but some of the blame must go to Simon himself.
To explain: after sorting out my many mis-typings, I found it got jammed on line 90 of the example program in the July issue in a never-ending loop and it was only after trying every bug-tracing stunt I could think of that I eventually found the cause. Unlike nearly all the other variables, he introduced variable 'L' in capitals, no doubt aware that his daisywheel printer produced straight 'l's which could be confused with '1's. Unfortunately in line 6755 he puts 'LET t1=INT(u+l)/2': so of all the '1's appearing in his program, this one happened to be not one at all. I cannot help wondering how many of your readers got bomboozled like me, and may have sent off for a cassette in desperation.
Maybe at my advanced age I 		should not be concerning myself with computers. On the other hand, I want to keep my fast diminishing brain cells active as long as possible - but not by hacking into Jet Set Willy.
Looking forward to the next issue of Your Spectrum.
H E Hammond, Luton, Bedfordshire

How else could we get you all to buy the tape? But seriously, Mr Hammond, thank you very much for sorting out the bug. We've had the odd problem with ZIP, but overall I hope that all who've mastered the program will agree that it's probably the best compiler on the market. Ed.
 

AVAST YE SOFTWARE HOUSES

I am anxious to comment on a subject foremost in my mind at the moment - software piracy.
In the older days of the Spectrum, everybody copied their friends' tapes with two tape recorders - but now, this is being made impossible by a new technique being employed by the tape-to-tape protection system (any of you pirates noticed it yet?). 		This new system is making home copying and commercial piracy a thing of the past (I always imagine commercial pirates having huge Hi-Fi systems recording tape-to-tape at double speed). Since a lot of pirates probably find the tape copiers available slow and boring, this should bring down piracy to a tolerable level.
OK, all well and good, the companies have found a great way to beat most pirates - but still companies are obsessed with putting more and more protection into the software. I've spent an incredible amount on software, over £30 on Microdrive transfer tapes alone and, having beaten the major software pirates, I see no reason why the software houses should make it difficult for us Microdrivers. They consistently add new protection methods as the old ones are discovered and beaten. Some of the protection methods seem to have been written specifically to stop the program being put onto Microdrive!
Having bought many of the latest software titles, it was my annoyance at not being able to transfer them to Microdrive that urged me to write this letter. Please, software houses, have a heart for us menials with 		Microdrives.
Richard Harrison, Forest Hill, London

When you start getting onto the subject of piracy, you're treading on very shaky ground. Although Your Spectrum in no way condones the pirates, there is a very thin line between actual piracy and putting software you have bought onto a different media for ease of use. If a software house made a program simple enough for anyone with a basic knowledge of computing to put it on to Microdrive cartridge - then a true pirate would see it as a gift. If the software houses actually included a 'Microdrive SAVE' option in the program, this might go some way to solving the problem. Unfortunately, we don't live in a perfect world, and software houses have nothing to gain except minimal increased sales through making their software Microdrive compatible. Even Sinclair Research doesn't include a 'Microdrive SAVE' option in its programs, so unless there's a pretty drastic change in the attitude of software houses towards Microdrives, I don't think we'll be able to do anything except resort to the ever-improving transfer tapes ... Troubleshootin 'Pete.
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