80-Bus News |
July–October 1982, Volume 1, Issue 3 |
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Page 28 of 51 |
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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
ce Lise hepets rd
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.
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