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TLD1985

Member Since 7 Feb 2012
OFFLINE Last Active Apr 8 2018 8:29 AM

Posts I've Made

In Topic: Todd Rogers banned from Twin Galaxies and records removed

Fri Feb 9, 2018 6:20 AM

All of this because some tired person working at an office desk in the early 80s; looked at a blurry photo of a CRT TV screen and misread a number as 5.51, wrote it down, sent off a badge and then just moved on with their lives and forgot about it.


In Topic: RCA Studio II GOLD MINE! An interview with the Studio 2 Production Manage...

Fri Feb 2, 2018 7:00 AM

This adds nothing to the technical understanding, but I now see how the error numbers display. :P

 

Attached File  errors.png   397.53KB   5 downloads


In Topic: RCA Studio II GOLD MINE! An interview with the Studio 2 Production Manage...

Thu Feb 1, 2018 7:32 PM

 

Awesome work getting these carts dumped - a great piece of history preserved!

 

There is some bad news however: the test cart uses some funky memory mapping, which means that it will not readily run on the multicart - or at least not without some  modifications... The author of Emma 02 figured out that the cart starts as normal, but quickly switches to an address in the 0x4000 range, where it expects the cartridge to be mirrored. Not entirely sure why it does this, but it seems to be needed to test the system's ROMs and RAM.

 

Interestingly, it also switches the machine to a high resolution mode (which is relative: 64 x 128), showing 4 memory pages: the top half is the top of the cartridge ROMs (0x0600-0x7FFF) and the bottom half is RAM (0x800-0x9FF). It then goes on testing the RAM, by filling it with 0xFF and writing 0x00 to the addresses and a few other patterns...

 

The hardware of the multicart doesn't map anything above 0x0FFF, because it only has a 4-bit latch - that means it has 12 address lines. A good thing is that if the console tries to use an address above that, it just sees the same, i.e. the first 4K are simply mirrored. But since the first 1K (0x0000 - 0x03FF) is mirrored to 0x4000 - 0x43FF (where the cartridge is expected to be), jumping into that region creates problems, i.e. a crash

 

It is however possible to patch the cartridge, so it stops jumping to an area that it not compatible with the multicart.

 

these are the patches needed:

0x0417  0x43 --> 0x07

0x041F  0x42 --> 0x06

0x0422  0x40 --> 0x04

0x0601  0x41 --> 0x05

 

This stops the program crashing: the memory test runs as does the one for the keypads. On my main test machine, it shows a 'digital failure' as it's called in the service manual by showing 3 & 4 in between the two keypads... I need to dig a bit deeper as to what this means, but it could be linked to not running the program from the correct memory bank... I've attached an image of the test card running on real hardware + multicart.

 

Also attached is a new image for the multicart flash memory, which includes the test card (in slot 4-6). I've moved the demo cart to this bank as well (4-7). Empty slots have a placeholder now, which shows an image on the Studio II (rather than black screen or crashing). If anyone needs this written to their flash chip: either contact me or anyone with an programmer that can handle a 39sf040 flash chip...

 

FliP

 

Would a system not getting enough amperage for the test to run also potentially cause error codes? The test cart is stated that it needs 500mA.


In Topic: RCA Studio II GOLD MINE! An interview with the Studio 2 Production Manage...

Tue Jan 30, 2018 8:28 AM

Great to know the final known US Studio II cart has now been dumped. (Ignoring any potential "betas" or tapes such as the possible colour demo of the Studio III)

 

 

A question to "ajavamind" (Andrew Modla) do you know/have any record of who the author of the tester cart was? I am guessing Joseph Weisbecker?


In Topic: RCA Studio II GOLD MINE! An interview with the Studio 2 Production Manage...

Tue Dec 19, 2017 2:14 PM

If it is THE same cart as in the service manual then it should output this:

 

testcart.png