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From: wbrown@beva.bev.lbl.gov (Bill Brown)
Newsgroups: comp.sys.cbm
Subject: Re: sx-64
Message-ID: <12962@dog.ee.lbl.gov>
Date: 8 May 91 19:57:38 GMT
References: <31.28280204@zswamp.uucp>
Reply-To: wbrown@beva.bev.lbl.gov (Bill Brown)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 56
X-Local-Date: Wed, 8 May 91 12:57:38 PDT

In article <31.28280204@zswamp.uucp> root@zswamp.uucp (Geoffrey Welsh) writes:
>In a letter to All, Bill Brown (wbrown@beva.bev.lbl.gov ) wrote:
>
> >In article <91127.091846XWUU@PURCCVM.BITNET> 
> >XWUU@PURCCVM.BITNET writes:
>>To the best of my knowledge, it is 100% C64/64C compatible.
>
> >There must be some differences - "Hess Forth" (cartrige) 
> >doesn't work in my sx - it just "hangs solid".  I've never
> >figured out why.
>
>   Bizarre!  As far as I know, the only difference between a Kernal 3 C64 and 
>the SX-64 is a change to make the RUN key (that's SHIFT-RUN/STOP) load from 
>the disk drive in stead of the cassette port (which the SX doesn't have).

The cartrige seemed to plug in ok - no mechanical problems that I could find.
I tried all the other (game) cartriges in the house and all worked fine.

Another person suggests that it could be a timing problem, due to the length
of the cable to the cartrige port.  I sort of doubt it - I'd expect a lot
of other things to break too.  Also, with a clock speed of around 1 MHz
I'd expect no problem.  The 6502 family is fairly easy to hook things up to.

At some show or other I talked to the people from MVP about the problem, since
Hess-forth is essentially fig forth with a few C= hacks added.  They could
shed no light on the problem, but they eventually came up with the home phone
number of the individual who did the port of fig forth to the '64.

I called him at home and he did eventually admit to having done the work.
As best as I can recall, he said that he was aware of the problem as he had
tried the cartrige in an an "sx" when they first came out.  It didn't work
for him but the issue was not persued.

A couple of things I tried:
	Just in case there was a difference in the PAL, I swapped with the
	PAL from a "standard" '64.  No change.

	I thought about swapping ROMs, but it seems to me there was a
	problem - I think the ROMs are different types - not the same
	number of pins. (It's been several years since I did all this.)

	I tried to figure out the address where things "hung" by `scoping
	the address lines, but that was a dead end.  I don't remember what
	I found, but it didn't help.

	I recall trying to compare the published entry points in the '64
	ROM to what was really in the "SX" ROM, but I didn't find anything.
	I think everything seemed to match.

Anyway, that's about all I can remember.  At this point it's probably not
important, and there's probably no way out.  Just another "feature."

Disclaimer:  These opinions are my own and have	    |
    nothing to do with the official policy or the   |  -bill
    management of L.B.L, who probably couldn't      |   wlbrown@lbl.gov
    care less about employees who play with trains. |