80-Bus News

  

July-October 1982, Volume 1, Issue 3











Page 28 of 51











28

Handling the printer was the next problem, characters are output at 9600 baud, which is a lot faster than the printer can print them. The printer has a 1K buffer, but this is soon filled. Fortunately the printer is equipped with a handshake signal which may be connected to pin 2 of SK2, signalling when the buffer is full, or the printer is out of paper, etc. A simple piece of software supervises the printer. Before sending a character the following code is called:

PUSH AF 3; Save the flags and the A register

? BUSY IN A,(0) ; Get the input into the A register RLA 3; Move the bit to be tested into the C flag JR C, BUSY 3; Test and loop if busy POP AF

After which the software may direct the character to be sent to the printer.

This finishes my summary of the major changes I have made to my Nascom 1, I

hope the above will be of help to someone, and that it will solve some of their problems. CEXTENDED Basic) F000 – FRFF booo —bFFF oR hooo -DFRE 7 b7 Basic] | Se] eric 6116 616] [Masa | 66} pore |- [2716] [2716] | vray! RAK RAM RAM fan RAM RAM EPpor EPAom a. iat I cy o ih a. ron > Alo ar Alt © ole 6 Polo oOo 7 O*1a 2 ols ob Oo O19 0 S721 US ot IE: 3335

? 90906 SPECIAL

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i WY

WIRING OF My own

SYSTEM GIVING THREE LkSf SWITCHABLE CONFIGLZATIONS Mom O-——-—-—-_ Oo00 VAAN @-——-—-© O00

Q@ O-FFF + GOK Ram Gare | Oloos , t @ s © 8k Bas + SZK RAM & Oren – sory : G2 oe oo – @ " {2k Basic + Bk RAM A Ocvee “ ; xRom bere f . owe My SPSTEM atsa HAS A YE Ghon Eoce FREE , fam f Boars usint. Abbnessts 1Leeo —CFFF

cnn emetic =m ann muna mee nummer: at em mamma iin rue

Link SetEcT Link SELEer Link SelecT For 4116 Ram Mobi ficarion ea last Fea switenaack Aja CHies Gib /erie Ale Coa 27h /2716 EF) CoD o olo o o ofo o oo 0 © 21 21 e oe 6 [ [ – | o 9 gh Anta a < “ 3’ eo 9 ‘ eo oo i 3 LINK @letk AK St RESISTOR

Pins 3&1I3

CONMELTED To

MoDIFICATIONS To ALLOW THE

1CG4 Must aE

Aiz @ Aal

USE

ANB EPROMS ON THE NASCOM 2.

OF 2ie RAMS JEFF ROLLASen 22


This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 28 of 51