Hi all! Did my message from this morning actually reach the list? I don't remember. Anyway, I was forwarding someone's questions about PET data transfer to the list (8032 with 8[02]50 drives). How is the IEEE-488 project for the PC going on? Here are a few notes from William Levak. He also sent the 1541 technical manual, which is available from <URL:http://www.funet.fi/pub/cbm/schematics/drives/new/1541/manual/>. I'll put (some of) the CBM II stuff from André online soon. Marko ---------- Forwarded message ---------- Date: Sat, 23 May 1998 23:43:00 -0400 (EDT) From: "William M. Levak" <wlevak@umich.edu> To: Marko Mäkelä <msmakela@cc.hut.fi> Subject: Re: 8296 system disk $E900-$EFFF on 8032 My 8032 is now running with a 2532 EPROM in $E000-$EFFF. The lower half contains the usual code. The upper half contains $60. The $60 is visible from the monitor program at $E900-$EFFF just as predicted. Since $60 is the machine language return instruction, I can sys to any location in the region and have it return back to BASIC. 8096 system disk The only program which is not on the 8296 system disk is 8032.mem.prg. This is actually a memory test program for the 64K board, not the 8032 memory. All the other programs are identical to the 8296 disk. 8296 programs BASIC4.0/80(d) and 50Hz screen editors This program is not on the 8096 disk. By comparing with ROM images I have determined that it is the BASIC 4.0 version with the newer $B000-BFFF ROM and the 50Hz 80 col. screen editor. This is the screen editor you have listed without the question mark. The version with the question mark is different only in the values loaded into the CRTC. I have tried these values on my 8032 and it definitely does not like them. The screen goes blank for a few seconds and then slowly comes back with much waviness of the image. The main problem appears to be the value loaded into register 0 (63). This would result in the image occupying only the central 5/8 of the screen. The horizontal oscillator appears to lose sync. and then resync at half the register 0 rate. The regular 50Hz values(without the question mark) produce a slight change in size and some waviness. From these experiments, it seems clear that the "?" version could not be for a 12" screen. It probably would not work on a 9" screen either. It appears to need a display with a higher horizontal scan rate. ---------- Forwarded message ---------- Date: Sun, 24 May 1998 23:44:33 -0400 (EDT) From: "William M. Levak" <wlevak@umich.edu> To: Marko Mäkelä <msmakela@cc.hut.fi> Subject: Re: 8296 system disk On Sat, 23 May 1998, William M. Levak wrote: > BASIC4.0/80(d) and 50Hz screen editors > ....... The main problem appears to be the value > loaded into register 0 (63). This would result in the image occupying > only the central 5/8 of the screen. The horizontal oscillator appears to > lose sync. and then resync at half the register 0 rate. The regular 50Hz > values(without the question mark) produce a slight change in size and some > waviness. From these experiments, it seems clear that the "?" version > could not be for a 12" screen. It probably would not work on a 9" screen > either. It appears to need a display with a higher horizontal scan rate. > I must try not to write technical explanations so late at night. The above explanation is, of course, wrong. Increasing the line length (reg. 0) increases the interval between sync pulses and decreases the sync rate. When the image loses sync and drops out, it would resync at twice the new rate, which is close to the usual rate. These values would still not be workable for a 12" display, but they might be OK on a 9" display. This might be the 50Hz equivalent of the 970150-07 screen ROM for the 60Hz 9" machine. This would most likely be an EPROM.
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