Making Mac128k HD20 Friendly

1 reply [Last post]
Joined: Mar 12 2005
Posts: 117

Hi all. I'm trying to figure out how to make the HD20 INIT load on a 128k Mac. Using the minimal system (ssw2.1/fndr 5.0) with HD20 v.1.0, I've reduced the system to bare bones -- in other words a system for which the 128k has more than enough RAM to load to free up the HD20 to load. This, however, was apparently not the problem. I'm going to try to Resedit out even more unused resources, but I still don't think this is the problem. I think it's a conspiracy by Apple to force its installed user base to upgrade to the 512k thus solving many problems they had by releasing a machine with so little RAM in the first place (more on that later).

But I think Apple intentionally crippled the HD20 from loading on a 128k and since the 128k uses the same 64k ROM that the 512k does (which loads it just fine thank you very much), the ONLY thing the HD20 can use to differentiate between the 128k and the 512k is the RAM. Either the HFS aware system, finder, or the INIT itself (or any combination of the three), checks the installed RAM reported by the system and if the value is less than 512k, the INIT refuses to load. If anyone else has any insight into this I would appreciate it. For now, I'm looking at the code, but I can't figure out where to start -- if I'm correct, it should be a simple matter to change the acceptable RAM value to something the INIT will allow to load on a 128k ... surely someone figured this out back in 85! I mean who would sit still after spending $2,500 to be excluded from using larger storage capacity?

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
Joined: Mar 9 2005
Posts: 79
Someone most likely also got

Someone most likely also got mad when they noticed it only took 3 resistors, a diode and 253 to 4x the ram. Silly apple... Wink They even went as far as outlineing the area to put the parts. Wink

Your project sounds interesting. Eventually when I get back onto the Mac kit I'll be looking into emulating an HD20 or disk drive.