Documentations about a sample of the Floppy-Speeder version: Professional-DOS Release
The table below contains some scan pictures of a Professional-DOS Release PCB, the ROM and tools disk, that was provided with it. There are also some descriptions (mainly PDF files) about the hardware listed, see the Hardware⇒Electronics-section of the Professional-DOS Version 1 for further explanations for these descriptions.
It's interesting to see, that some of the part numbers of the little TTL-ICs can be read. One is not polished and can be identified as a 74LS00. Another one isn't polished completely and can be identified as 74LS173 (not really simple).
Some ROM internals
The C64 kernal ROM version of this variant seems to be widely held, because it can be found on other web pages. Maybe because this version was the most used one (C64, C1541, userport connection).
Having a look into the disassembly of the drive ROM (partly), we can see similar routines as showed in Hardware⇒ROMs. The most important changes, that may come to your eyes is a change in the addressing from Professional-DOS Version 1 to the Release variant showed here. Not only the ROM location of the DOS expansion ROM changed from 0x9xxx to 0x6xxx, but the GCR tables also from 0x8xxx to 0x7xxx. Additionally the half nibble tables aren't grouped by 256 bytes anymore (0x80xx/0x81xx) but by 2048 bytes (0x70xx/0x78xx).
Hardware differences (floppy expansion PCB)
The addressing changes are caused by some changes in the hardware of the drive expansion PCB and the address decoder which is built with a simple 32 byte PROM.
In comparison to the schematic explained in Hardware⇒Electronics, the main difference is, that address line A11 is now used for simulating unused external addresses; instead of address line A13. This requires the address line A11 as input to the PROM address decoder instead of A8 and causes the ROM code changes showed above. A change independent from the A11 address line change is, that the Flip-Flops are now set by writing different addresses in the address range from 0x6800 to 0x6fff.
Another change is, that the ROM chip select signal (/CE) is now switched together with the ouput enable signal (/OE). It seems, that the GND connection between pins 1 and 21 of the 6502 processor was cut on the PCB of this revision. Maybe because of a complicated layout of the PCB.
Summarized, the RAM/ROM mapping of the release variants of Professional-DOS is as following: