Archived a few PERQ games...

Tony Duell ard at
Sun Aug 20 17:37:47 CDT 2006

> >
> > It may not matter. From what I rmemberm the infromation is stored 
> > elsewhere too (probably in the file descriptor blocks). THe pointers in 
> > the headers are used for speed and to help recover the filesystem in the 
> > event of disk problems.
> Yes, I was wondering about this as well.  The POS documentation mentions 
> this header information as being present on disk but doesn't describe it 
> in detail.  The UnitIO "DiagRead" command returns an 8-word block of 

Yes, one of the things the manual misses out...

> header data on a block read -- I don't know if this has any relationship 
> with the physical bits on the disk; but just in case I made sure to copy 

My guess is that it's just the data in the header. There'd be no reason 
to modify it.

> those along with the 256 words of actual sector data.
> At any rate, the header data doesn't appear to be necessary for parsing 
> the directory structure; I've written another quick and dirty utility 

It's not... It's used either for efficiency (to avoid having to go back 
and read/interpret the file descriptor to find the next block of the 
file) or to halp re-create the file descriptor if it gets corrupted 
(conversely the file descriptor can be used to recreate these pointers in 
the header).

> (on the PC this time) to read in the disk image and dump the directory 
> structure and files to disk without too many hairy issues.  (The utility 
> and all the files on the disk are now on my website at 

I really must find time to look at that...

> Nothing too incredibly exciting on the disk, but it's nice to have it 
> archived for posterity.
> > Do you have the POS source code? I thin I hace most of the Pascal (not 
> > microcode, though) sources for one version.
> >   
> I do not -- what I have on the PERQ is the bare minimum necessary to 
> compile and link pascal programs.

I've got 7 .zip files here, around 250K each. They contain pascal sources 
for most of POS (I know the pascal compiler itself is not there :-(). And 
some microcode, etc for the 'testbed'. I can e-mail you copies (or is 
there somewhere I should send these to be made available?)
> One quick question:  Any ideas what digitizer pucks are compatible with 
> the BitPadOne?  My PERQ came with a very very crude home-made puck 
> (  It 
> just barely works (the cursor jumps all over) and it's falling apart.  
> I'd love to replace this with something more authentic.  Or at least 
> something that works correctly.

There were 4 official pointing devices for this tablet : 

A pen-like thing. This came in 2 versions, one could be pulled apart i 
nth emiddle to put a ballpoint refil in, the later one couldn't. Pressing 
the pen point is equivalent to one of the buttons on the true pucks

A single-button puck

A 4 button puck. This is the correct one for the PERQ. It's the same as 
the single-button one with 3 more switches soldered in (in other words 
you can convert a single-button puck into a 4 button one.

A 13 (?) button puck. I have no idea how this works, there must be an 
interneal diode matrix or something. The tablet only has 4  button input 
lines, and AFAIK there is no power line on the puck connector.

As to whether or not you can use other pucks. The buttons, IIRC, just 
ground the appropirate line from the tablet. The sense coil is about 12mm 
in diameter, and IIRC around 30 turns of wire. There's no electronics in 
the puck. Of course piunotus are in the manual (I have that if you need 
said pinouts).

If the home-made puck is not reliable, I'd suspect noise pickup on the 
coil wiring. It's a pretty small signal. Maybe some careful screening 
would help (the real pucks have copper foil in strategic places.


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