Editing motorola/mc14500/mc14500b

{{motorola title|MC14500B}}
{{mpu
| name                = Motorola MC14500B
| image               = <!-- actual image to use                                                     -->
| caption             = <!-- caption for the image specified                                         -->
| manufacturer        = Motorola
| model number        = MC14500B
| part number         = MC14500B
| market              = Industrial
| first announced     = 1976
| first launched      = 1976

| frequency           = 1 MHz

| process             = 
| technology          = CMOS
| word size           = 1 bit

| electrical          = yes
| power               = 500 mW
| temp max            = 125 °C
| temp min            = -55 °C

| packaging           = Yes
| package             = DIP16
| package type        = DIP
| package 2           = CerDIP16
| package type 2      = CerDIP
}}
The '''Motorola MC14500B''' or '''Industrial Control Unit''' ('''ICU''') is a {{arch|1}} [[microprocessor]] designed by [[Motorola]] and released in 1976. Production continued well into the 1990s. The MC14500B was designed as an extremely low cost [[programmable logic controller]] suited for implementing various [[ladder logic]] circuits as replacement for older relay-based systems.

== Architecture ==
The MC14500B is a true {{arch|1}} microprocessor - all operations are done on single-bit operands. The MC14500B comes with an internal clock that may be controlled via an external resistor. While designed to run at 1 MHz, it may be tuned down to 10 KHz or hooked up to an external clock altogether.

The MC14500B does not include any on-chip memory nor a [[program counter]]. A program counter is not provided because this MPU has no notion of memory at all, and by extension no notion of addresses. It implements an early [[Harvard architecture]] type of flow where separate instruction lines and data lines are fed to it. Individual instructions and values are fed in each clock cycle and the result can be read via a number of output lines. Typically a [[PROM]] chip such as the {{motorola|MCM7641}} and PC such as the {{motorola|MC145168}} were used to form a complete system. Because this was done externally, in theory at least, this MPU can support any amount of memory needed.

The MC14500B has a number of output lines to help facilitate [[subroutine]] returns, [[branching]], [[conditional]], and general purpose I/O. However since there are no built-in support for memory or addressing, they have to be dealt with externally, possibly with some glue chips.

=== Registers ===
The MC14500B has a single [[register]]: '''result register''' ('''RR''') which always stores the value of the intimidate operation that has been performed. RR can be read directly from pin 15 at any time. RR is also always used as the 

=== Instruction Set ===
{| class="wikitable"
|-
! Mnemonic !! OPCode !! Action
|-
| NOPO || 0x0 || RR → RR ; Flag O → 1
|-
| LD ||  0x1 || Data → RR
|-
| LDC ||  0x2 || <span style="text-decoration:overline">Data</span> → RR
|-
| AND ||  0x3 || RR · Data → RR
|-
| ANDC ||  0x4 || RR · <span style="text-decoration:overline">Data</span> → RR
|-
| OR ||  0x5 || RR + Data → RR
|-
| ORC ||  0x6 || RR + <span style="text-decoration:overline">Data</span> → RR
|-
| XNOR ||  0x7 || If RR = Data, RR → 1
|-
| STO ||  0x8 || RR → Data ; Write → 1
|-
| STOC ||  0x9 || <span style="text-decoration:overline">RR</span> → Data ; Write → 1
|-
| IEN ||  0xA || Data → IEN
|-
| OEN ||  0xB || Data → OEN
|-
| JMP || 0xC || JMP Flag → 1
|-
| RTN ||  0xD || RTN Flag → 1
|-
| SKZ ||  0xE || Skip next instruction if RR = 0
|-
| NOPF ||  0xF || RR → RR ; Flag F → 1
|}

== Documents ==
* [[:File:MC14500B datasheet.pdf|MC14500B Datasheet]]
* [[:File:Motorola MC14500B Industial Control Unit Handbook.pdf|Motorola MC14500B Industial Control Unit Handbook]]
base frequency	1 MHz (0.001 GHz, 1,000 kHz) +
core voltage	5 V (50 dV, 500 cV, 5,000 mV) +
core voltage tolerance	5 % +
designer	Motorola +
family	MC14500 +
first announced	1976 +
first launched	1976 +
full page name	motorola/mc14500/mc14500b +
instance of	microprocessor +
ldate	1976 +
main image	+
main image caption	1-bit MC14500BCP +
manufacturer	Motorola +
market segment	Industrial +
max case temperature	398.15 K (125 °C, 257 °F, 716.67 °R) +
max storage temperature	423.15 K (150 °C, 302 °F, 761.67 °R) +
min case temperature	218.15 K (-55 °C, -67 °F, 392.67 °R) +
min storage temperature	208.15 K (-65 °C, -85 °F, 374.67 °R) +
model number	MC14500B +
name	Motorola MC14500B +
part number	MC14500BCL +, MC14500BCP + and MC14500BAL +
power dissipation	0.5 W (500 mW, 6.705e-4 hp, 5.0e-4 kW) +
technology	CMOS +
word size	1 bit (0.125 octets, 0.25 nibbles) +