Service manual

H/Z-100 Service Bulletins
FSB-Z100-004: Changes to Service Data Manual
Please make the following changes in your Z-100 Service Data Manual:
- On page 3-159, middle column, change U219 from 74ALS74 to 74S74.
- On page 4-13, third paragraph, change "...logic zero on VDRAMSEL (U337-4)
and..." to "...logic zero on VIDRAMSEL (U377-4) and..."
- Schematic MB1:
-- Locate C178 & C179 at the crystal inputs to the 8085 CPU (U210). Note that
these capacitors may not be installed, as the crystal used at Y101 did not require
them to operate. (To my knowledge, these capacitors were never installed - ed.)
-- Locate U198-11 at the data output latch. This line connects to U220-12, so the
correct mnemonic is CPUWR, not CPUWR as indicated in an earlier update.
-- Locate U188-7 in the swap timing circuits and mark it "88SELD." This line goes to
the extended addressing circuits at U193-1, to NDEF(8088) at U215-2, and to the
status circuits at U226.
Refer to the table shown below as you update your schematic.
IC Location From To
U211-23 8088 CPU Z H
U219 Bus Ctrl Out ALS74 S74
U219 Bus Ctrl Out 443-1051 443-900
U220-12 Bus Ctrl Out L P
U237D Bus Ctrl Out ALS74 LS125
U237D Bus Ctrl Out 443-1051 443-811
U202-9 Interrupt latch L P
C189 Reset circuits 22/10 100uF
D101 Reset circuits 1N4149 1N5817
U226-13 Status circuits A0 A3
U226-13 Status circuits 88SEL 88SELD
- Schematic MB3
Refer to the table shown below as you update your schematic.
IC Location From To
U151-11 refrsh-Wait Timg H P
U170-10 Refrsh-Wait Timg H P
U151-13 Refresh Timing H P
U167-8 Refresh Timing H P
- Schematic MB4
Refer to the table shown below as you update your schematic.
IC Location From To
U160-1 thru -8 Timer Z P
U204-35 Keyboard Encoder H L
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