Radio Shack 16B Reference Handbook

MREQ
240
19 2MREQ *"
®
(TO Z23, pins 4 and 12)
SEE
,HEET
2
KEf
IOARD
ROM
@
--
--
ROM
'"
08~
M
07
'T6'
"
AI3 3
J
TO
AI4
4
238
AI5
5
(pi n$
10,12,61
GND
29
MREQ
R9 ®
~~___ D
r ---------~~,
I I
I I
R8 I
QS lOOK •
I MPSS3906 I
I cia + CI4 CRI I
: I~t:~ O'~~eF¢ :~~/:3S :
I I
;;sv I~ 0'11~0~ I
)0 I 29 (32 PLACES) I
; PL AC E::A 37 C2 2,C2 3, C29, I
16-C19 C31,C33,C3S-C38,
I '39 C40,C41, C44-C56 I
L ~
(Revision D and after)
ROM '"
- .,
74LS011l
R62
47K
L--.JVV'v-_-+_---()-+ 5v
Is
14
13
qRJ
Z3
I
4--· I
1.'74 b..;:6 ........ --'M"'E:.:.Mc.....:;'le.-
)-'8~---'S::..j - f I
74LSe0 : ~
I
I
I
I
I __ J I
L ~_--------J
RD'" 13
RAM·
A. Pins 5 and 4 of Z74 connect directly to signal ~MREQ*.
B. Pins 20 of Z33 and Z34 are tied together.
C. DIP shunt Z3, pins 6,7 and 8 are tied together and go to pins 20 of Z33 and Z34.
The signal
is now called ROM*.
D. Pin 39 is now ground. +5 volts still goes to 0.1 MF capacitors (32).
Figure 28. Changes to the TRS-80 Schematic Diagram (Figure 29)
(Revisions D and E)
III

Radio Shack 16B Specifications

General

Brand	Radio Shack
Category	Desktop
Input	Keyboard
Ports	Serial, Parallel
Type	Personal Computer
Power Source	Mains AC
Functions	Business applications, word processing, data management
Model	TRS-80 Model 16B