F8 chip was Video Brain

From: Paul E Coad <pcoad_at_crl.com>
Date: Mon Jul 14 02:28:51 1997

On Mon, 14 Jul 1997, David Williams wrote:

> On 13 Jul 97 at 17:17, Charles P. Hobbs wrote:
> > I remeber reading a little blurb about Video Brain in the April 1981
> > Creative Computing. Essentially, by that time the company had gone out
> > of business. . .
> I missed the little blurb in my April 1981 issue but do see a couple
> of articles on the Video Brain in the Feb '79 and Mar '79 issues of
> Creative Computing. Says they used the F8 processor. I've heard of
> it but don't know much about it. Anyone know how it compared to say
> the 8080 which the article says was the other processor they
> considered using.

The F8 was made by Fairchild. IIRC is was the brain of the Channel F
video game system. The blurb below is from the "Microprocessor
Cookbook" by Michael F. Hordeski (this is a TAB book and I am typing, so
be careful).

The F8 is a multichip NMOS microprocessor system that is designed around
a bus architecture. The heart of the system is the CPU chip. When this
combind with the program storage unit (PSU) which contains a masked ROM,
timing and interrupt control, a minimal system configuration is obtained.
The memory interface unit contains the memory address registers and
address buss not contained in the CPU. The DMA chimp contains the hold
and wait circuitry required for direct memory access.

The CPU chip contains sixty four bytes of scratch-pad memory which can
eliminate the need for random-access memory in simple applications.

The data bus provides the external interface through two sets of eight-
bit input/output ports. Transfer gates are used to move data
from the data bus and external busses for processing. The CPU chip also
includes a clock and power-on-reset circuits, but it does not contain a
program counter or memory address registers. These are included in one
of the companion chips. Without the address registers there is no need for
an address bus, and this reduces the CPU chip count.


The F8 was a 2 chip design (there was a later 1 chip version). The
main competitor was the Intel 8048. Below is a comparison chart from
"Microprocessors from chips to systems" by
Rodnay Zaks:

                             8080 F8
Technology PMOS NMOS
# of Instructions 69 70
Cycle Time (uS) 1, 3, 1.5, 2 2 to 13
Direct addressing (bits) 16 16
Registers 7 1 + RAM
Stack(levels) soft external sp
interrupts 1 1
on-chip clock - -
        ROM(bytes) - -
        RAM(words) - 64
        timer - -
        PFR - -
I/O lines - 16
package (pins) 40 40
Power supply (V) +5, -5, +12 +5, +12


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Received on Mon Jul 14 1997 - 02:28:51 BST

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