Micro­power

  

Volume 2, Number 1 – February 1982

Page 28 of 37

LETTERS

Dear Sir,

Re the “Nascom 1 Keyboard Upgrade”, an interesting article currently under construction, readers may be interested to know that Licon Keys (the later angled variety) are available from Target Electronics, __, ______ ____, Bristol, ___ ___. Prices in December 1981 were; Keyswitch 65p each., Keytop 17p each. My only criticism of the magazine “so far” is that the density of the type varies considerably, some is difficult to read.

On expanding my Nascom 1 to include a 64K RAM card, EPROM expansion card with 8K Basic running under Nasbug T4 I encountered a hardware problem. Executing FOR loops with large values, i.e., greater than 1000, produced “crashes”; Basic programs occasionally jump to machine code, and vice versa. After considerable difficulty I tried connecting a thick lead (20 A current capability) directly from the Z80 earth pin to 0 V on the Buffer board. To date this has cured all programming problems.

P. E. Acton, Leicester


Dear Sir,

In the program “Rings of Hanoi” on p. 31 of the December issue of Micropower, I think the following corrections are needed:–

220 A (I, 0) = I:A(I ,1) = 0: A (I, 2)=0
290 SCREEN 1,1: PRINT : SCREEN 6,15
400 GOSUB 920: SCREEN 2,2:PRINT: SCREEN 2,2: PRINT "MOVE FROM";
410 INPUT IN$
420 GOSUB 1300:TF=IN:IF TF < 0 THEN 400
440 SCREEN 1,1:PRINT:SCREEN1,1
470 GOSUB 920:SCREEN 2,2:PRINT: SCREEN 2,2: PRINT "TO PILE";

F. Johnson, Stockport


Dear Sir,

The content of Micropower is quite good and the technical level is about right, I think the hardware/​software mix is probably O.K., although I would personally like to see more programs in each issue. I have managed to make the “Snowdinger” mod work at 2 Mhz and 4 Mhz, although I have had to delay the WAIT signal by two gate propagations in order to get the system to operate at 2 Mhz. The improvement in screen quality is excellent.

The dual monitor (2716 for 2708s) was nearly correct, though it is not permissible to wire ‘or’ the two outputs of a 74LS139 – it is necessary to combine the signals correctly by using, for example, a 7402.

D. R. Piercy, Wareham


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