Re: Unknown holes in the motherboard of the CBM610

Ruud,
I have another for you, which is related. The "Alternate OS" board:http://www.6502.org/users/sjgray/computer/cbm2/ace-os.jpg

This is an advertisement for it and other products including the 1024K board. The 1024K board mounts on the Low Profile machines (610, B128 etc) only. It plugs directly into the expansion sockets and it provides two pass-thru header connections for the Alternate OS board. The pass-thru connectors are spaced exactly like the LP motherboard connectors but are offset towards the back of the machine so that the Alternate OS board mounts on top in such a way that it does not interfere with the internal LP keyboard.
I have not seen a picture of the Alternate OS board, so I don't know if there are any remaining specimens out there. I don't know if Gary Anderson is still around to provide more info. I only know of 2 owners of 1024K boards and I assume that not many of them were made, so I'm not sure you really need to worry about being compatible with them.
My personal feeling is if you're re-making the CBM-II motherboard then you should be able to do 1024K directly on the new motherboard, and maybe even duplicate the Alternate OS board simply by making the ROM sizes bigger and adding a switch (or circuit) to control the upper address line(s).
Steve


      From: "Baltissen, GJPAA (Ruud)" <ruud.baltissen@apg.nl>
 To: "'cbm-hackers@musoftware.de'" <cbm-hackers@musoftware.de> 
 Sent: Thursday, April 26, 2018 8:21 AM
 Subject: RE: Unknown holes in the motherboard of the CBM610
   
#yiv6309959412 #yiv6309959412 -- _filtered #yiv6309959412 {font-family:Helvetica;panose-1:2 11 6 4 2 2 2 2 2 4;} _filtered #yiv6309959412 {font-family:Helvetica;panose-1:2 11 6 4 2 2 2 2 2 4;} _filtered #yiv6309959412 {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;}#yiv6309959412 #yiv6309959412 p.yiv6309959412MsoNormal, #yiv6309959412 li.yiv6309959412MsoNormal, #yiv6309959412 div.yiv6309959412MsoNormal {margin:0cm;margin-bottom:.0001pt;font-size:12.0pt;font-family:New;}#yiv6309959412 a:link, #yiv6309959412 span.yiv6309959412MsoHyperlink {color:blue;text-decoration:underline;}#yiv6309959412 a:visited, #yiv6309959412 span.yiv6309959412MsoHyperlinkFollowed {color:purple;text-decoration:underline;}#yiv6309959412 p.yiv6309959412msonormal, #yiv6309959412 li.yiv6309959412msonormal, #yiv6309959412 div.yiv6309959412msonormal {margin-right:0cm;margin-left:0cm;font-size:12.0pt;font-family:New;}#yiv6309959412 p.yiv6309959412msochpdefault, #yiv6309959412 li.yiv6309959412msochpdefault, #yiv6309959412 div.yiv6309959412msochpdefault {margin-right:0cm;margin-left:0cm;font-size:12.0pt;font-family:New;}#yiv6309959412 span.yiv6309959412msohyperlink {}#yiv6309959412 span.yiv6309959412msohyperlinkfollowed {}#yiv6309959412 span.yiv6309959412e-mailstijl17 {}#yiv6309959412 span.yiv6309959412e-mailstijl18 {}#yiv6309959412 p.yiv6309959412msonormal1, #yiv6309959412 li.yiv6309959412msonormal1, #yiv6309959412 div.yiv6309959412msonormal1 {margin:0cm;margin-bottom:.0001pt;font-size:11.0pt;font-family:New;}#yiv6309959412 span.yiv6309959412msohyperlink1 {color:blue;text-decoration:underline;}#yiv6309959412 span.yiv6309959412msohyperlinkfollowed1 {color:purple;text-decoration:underline;}#yiv6309959412 span.yiv6309959412e-mailstijl171 {color:windowtext;}#yiv6309959412 span.yiv6309959412e-mailstijl181 {color:#1F497D;}#yiv6309959412 p.yiv6309959412msochpdefault1, #yiv6309959412 li.yiv6309959412msochpdefault1, #yiv6309959412 div.yiv6309959412msochpdefault1 {margin-right:0cm;margin-left:0cm;font-size:10.0pt;font-family:New;}#yiv6309959412 span.yiv6309959412E-mailStijl29 {color:#1F497D;}#yiv6309959412 .yiv6309959412MsoChpDefault {font-size:10.0pt;} _filtered #yiv6309959412 {margin:72.0pt 72.0pt 72.0pt 72.0pt;}#yiv6309959412 div.yiv6309959412WordSection1 {}#yiv6309959412 Hallo Steve,       >There is also a 1024K memory board by Anderson Communications Engineering: >http://www.6502.org/users/sjgray/computer/cbm2/pic-ace-b1024.jpg    Thank you for this info!    The JPG looks as if the board uses female headers at the under site of the board for both big expansion connectors (*) and the small one at the other side. IIRC the position of the smaller connector in the 610 is different from the one in the 720 and that would explain the connector in the left of the JPG. You can see clearly the lines that connect it with its female counterpart. So for one of the computers you'll need a flatcable. Could you tell me in which system the board would fit w/o using the flatcable, please?    Anyway, both your cards are enough reasons for me to keep the connectors and holes fixed to each other. But I will design them as a separate package so I still have some flexibility in placing the whole on the motherboard. Another idea: why using two different layouts, why not using the one for the 720 for both the 720 and 610 (or the other way around)? Comment is welcome!    (*): why two? Why isn't one enough? Both connectors are the same AFAIK. Or is here another difference in layout between the 610 and 720? I'll definitely have to check this this evening.      Met vriendelijke groet / With kind regards, Ruud Baltissen    www.Baltissen.org             


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