"Numm not heard of that one does it have any other markings ?" All the numbers on the biggest chip are
451 VA 4428 VL 4500 A-15PC TNS 4500 AN-15 KOREA "How many memory chips are fitted currently " 8 with 8 spare Lee - Back to the QL- ----- Original Message ----- From: Phill Harvey-Smith To: ql-us...@q-v-d.com Sent: Thursday, March 10, 2011 11:34 PM Subject: Re: [Ql-Users] Medic board On 10/03/2011 23:24, Lee Privett wrote: > Of the three large chips, one is an EPROM 2764(middle), the one below > is an 8059 or WD1770 That'll be the disk controler, WD1770, I suspect the 8059 is a date code. Odd that it's only got a 2764 (8K) eprom, most of the QL innterfaces had either a 27128 (16K) or 27256 (32K). > and the largest chip is marked as a 4500A. The > memory chips are M5K4164 and I suppose that filling the other 8 empty How many memory chips are fitted currently ? 4164s are 64K x 1bit, so a group of 8 gives you 64Kbytes of ram. If there are only 16 RAM sockets and you filled them with 2764s that would give an extra 128K total. It may be of course that you can populate them with 41256 which are pinout compatible (apart from having an additional address line on pin 1), to give two banks of 256K for a total of 512k expansion, but that would depend on the other logic on the board. Cheers, Phill. -- Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric ! "You can twist perceptions, but reality won't budge" -- Rush. _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
