On 08/07/2016 10:56 PM, Segher Boessenkool wrote: > On Sun, Aug 07, 2016 at 09:44:04PM +0200, Gerrit Heitsch wrote: >>> http://segher.ircgeeks.net/vic-ii/8565-blocks.jpg >>> >>> (that is 8565, not *entirely* the same as 6567/6569, but I labeled the >>> blocks here). >>> >>> This is 6569 (R3): >>> >>> http://retronn.de/imports/cbm_chips/vic2_overview_gray4.jpg >>> >>> and this is R1 (warning, huge): >>> >>> http://mail.lipsia.de/~enigma/vic2r1/fullvic_lowquality.jpg >>> >>> (not much has changed in R3). >> >> Likely some timing issues. > > Well, obviously the digital video signals were pinned out, like on the > 8565 (see the octagonal pads at the right). This is for testing only > I think, the drivers for those pads are very weak. The drivers look to be about one third to half the size as the drivers for the address lines. >>> 6566 6567 >>> 17 phi0 phi0 >>> 18 phiin #RAS >>> 19 phicol #CAS >>> 20 Vss Vss >>> 21 A0 phicol >>> 22 A1 phiin >>> 23 A2 A11 >>> 24 A3 A0/A7/A8 >>> 25 A4 A1/A8/A9 >>> 26 A5 A2/A9/A10 >>> 27 A6 A3/A10/A11 >>> 28 A7 A4/A11/A12 >>> 29 A8 A5/A12/A13 >>> 30 A9 A6/A13/1 >>> 31 A10 A7 >>> 32 A11 A8 >>> 33 A12 A9 >>> 34 A13 A10 >> >> Hm? What do you mean with the 3 Adress lines on a single pin of the >> 6567? The schematics of the C64 only show 2 per adress line. > > row address / column address for 7-bit ram addressing / column address for > 8-bit ram addressing. It is a metal mask option on the VIC chip. > > As you see the 7-bit is much neater. Yes, but VIC in general looks hacked together with the multiplexed/non-multiplexed address line mix. > >>> Btw, the RAS/CAS things are self-timed, using analogue delays, long >>> inverter chains etc. >> >> There should be differences between R1 and R3 in this area since R1 >> wants a 82pF Capacitor between CAS and GND while it's not needed for R3. > > Interesting! The source for this detail is here in the lower right corner: ftp://www.zimmers.net/pub/cbm/schematics/computers/c64/251138-1of2.gif Also, the PLA with the number MB112A101 exists, was made by Fujitsu (as indicated by the 'MB' and the case design) and has the Commodore part number 251064-01. I have a working one. Its HIGH level seems to be a tad below what the MOS PLA produces. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2016-08-08 06:00:03
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