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Path: ns-mx!uunet!wupost!waikato.ac.nz!comp.vuw.ac.nz!actrix!David.Empson From: David.Empson@actrix.gen.nz (David Empson) Newsgroups: comp.sys.apple2 Subject: Re: memory mapped locations ($0CXXX) needed for printer, serial ports. Message-ID: <1991Aug31.143948.10353@actrix.gen.nz> Date: 31 Aug 91 14:39:48 GMT References: <3275@pdxgate.UUCP> Organization: Actrix Information Exchange, Wellington, New Zealand Lines: 91 Comment-To: kevins@eecs.cs.pdx.edu In article <3275@pdxgate.UUCP> kevins@eecs.cs.pdx.edu (Kevin Stanton) writes: > > I am attempting to use my Apple II+ as a printer buffer (serial in, > parallel out). However, my Super Serial Card manual is rather sparse on > details, as it is strictly a users manual. I'm assuming you are using assembly language here. Is this a real Apple Super Serial Card, or a clone of it? Even the clone SSCs that I've seen come with a full manual. > It gives certain entry points, but they are blocking, not polling. Which entry points are these? The BASIC interface is entirely blocking (JSR $Cn00 to set up, then use COUT and RDKEY to get or send bytes). The Pascal interface's I/O calls are also blocking, but there is a status call, which you can ask 'are you ready for output' and 'do you have any input available'. To confirm that your card has the Pascal interface, check the following bytes (assuming the card is in slot 's'): Signature bytes: $Cs05 = $38, $Cs07 = $18, $Cs0B = $01. The entry points for the Pascal interface are contained in a lookup table starting at $Cs0D. Each table entry contains the low byte of the start address of the corresponding routine. The high byte is $Cs. $Cs0D offset to INITIALIZE routine $Cs0E offset to READ routine $Cs0F offset to WRITE routine $Cs10 offset to STATUS routine For example, if $Cs0D contains the number $44, the initialize routine starts at $Cs44. All the routines must be called with X containing $Cs and Y containing $s0 (e.g. $C2 and $20 for slot 2). WRITE: A contains byte to write READ: Byte read is returned in A STATUS: A=0 for 'are you ready for output', A=1 for 'do you have input ready'. In both cases, the SSC will return with carry set if the answer to the question is 'yes'. You could go down to the hardware level if you want. Use the serial firmware to initialize the card (baud rate, etc.) To transmit: LDX #$s0 ; s is slot number, e.g. $20 for slot 2 LDA $C089,X ; read status register AND #$10 ; test Transmitter Empty flag BEQ IsBusy LDA Byte_to_send ; get the byte you want to transmit STA $C088,X ; stick it in the transmit data register To receive: LDX #$s0 ; s is slot number, as above LDA $C089,X ; read status register AND #$08 ; test Receive Full flag BEQ NoByte LDA $C088,X ; get the received byte STA Byte_received > I also seem to be unclear in regard to initializing the devices (can > both the printer card and the SSC be active at the the same time? Using the BASIC interface, you can only have one input device and one output device. For example, in Applesoft BASIC, you can do a PR#1 to output to slot 1, and an IN#2 to input from slot 2. If you use the PASCAL interface or talk to the hardware directly, you can do simultaneous I/O to as many slots as you like. > The printer card is an Apple Dumpling, and is equally spare in > details. All it gives is a sample 12 line driver which I can't seem > to get to work. Sorry, I know nothing about this card. Check the above ID bytes to see if it supports the Pascal interface. If it does, you're home free. If it doesn't,... I've given you half the solution, anyway. -- David Empson USENET: David.Empson@bbs.actrix.gen.nz