A microprocessor design company started by some ex-Motorola designers, shortly after
the Intel 8080 and Motorola 6800 appeared, in about 1975. MOS Technologies introduced
the 650x series, based on the Motorola 6800 design, though they were not exact clones
for legal reasons.
The design goal was a low-cost (smaler chip) design, realized by simplifying the
decoder stage. There were no instructions with the value xxxxxx11, reducing the 1-of-4
decoder to a single NAND gate. Instructions with the value xxxxxx11 actually executed
two instructions in paralell, some of them useful.
The 6501 was pin-compatible with the 6800 for easier market penetration.
The 650x-series had an on-chip clock oscillator while the 651x-series had none.
The 6510 was used in the Commodore 64, released September 1981 and MOS made almost
all the ICs for Commodore's pocket calculators.
The PET was an idea of the of the 6500 developers. It was completly developed by
MOS, but was manufactured and marketed by Commodore. By the time the it was ready
for production (and Commodore had cancelled all orders) MOS had been taken over by
Rockwell (Commodore's parent company). Just at this time the 6522 (VIA) was finished,
but the data sheet for it was not and its developers had left MOS. For years, Rockwell
didn't know in detail how the VIA worked. .
Floppy Disk Drive for OSI
8" drives used 50 pin connectors,
5.25 and 3.5 drives used 34 pin connectors
5.25" 8" Function
4 18 Head load (-in-)
6 32 Drive select 4 (-in-)
8 20 Index sector pulse (-out-)
10 26 Drive select 1 (-in-)
12 28 Drive select 2 (-in-)
14 30 Drive select 3 (-in-)
16 Motor on (-in-)
18 34 Step direction (in or out) (-in-)
20 36 Step pulse (-in-)
22 38 Write data (-in-)
24 40 Write gate (enable write) (-in-)
26 42 Track 0 pulse (-out-)
28 44 Write protect (-out-)
30 46 Read data (-out-)
32 14 Side select (-in-)
34 22 Ready (-out-) (If not available index pulse may be used)
Disk Sector Directory DIR <tt> (tt=00-76)
List Disk Directory RUN "DIR"
Create New File RUN "CREATE"
Delete Disk File RUN "DELETE"
Rename Disk File RUN "RENAME"
Copy Disk Or Disk Files RUN "COPIER"
Copy Data Files RUN "DATRAN"
Compare Disks Or Files RUN "COMPAR"
Sort Records In A Disk File RUN "GOSORT"
Pack Files To Front Of Disk RUN "REPACK"
Fill A File With Nulls RUN "ZERO"
File Copy LOAD <file spec1>, PUT <file spec2>
Assign I/O Buffers RUN "CHANGE"
Load File LOAD <file spec>
Execute Binary File CA <adr>=<trk>, <sec>, GO <adr>
Execute Binary File In BASIC Workspace XQT <file spec>
Load File Into Memory CA <adr>=<trk>, <sec>
Load Track Into Memory EXAM <adr>=<tt>
Take Input From Disk File INPUT #<6 or 7>
Format Disk INIT
Format Single Track INIT <tt>
Send Output To Disk File PRINT #<6 or 7>
Save Memory To Disk File SA <trk>, <sec>=<adr>/ <sec>=<adr>/ <pages>
Save BASIC Workspace PUT <file spec>
Select Disk Drive SE <dev>
Direct Output To I/O Channel IO, <channel no>
Direct Input To I/O Channel IO <channel no>
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