Apple-1 Operation Manual 1976

The Apple-1 Operation Manual is Apple Computer Company's manual for the Apple I, issued from 770 Welch Road, Palo Alto, California. The manual itself carries no date; its schematic sheets (drawing 00101) are dated 10 March and 2 April 1976. The hosted scan has 15 pages: the cover, the specifications page, eight numbered text pages, a page of interfacing circuits, the warranty and the three schematic sheets.

Contents

• Specifications (PDF p. 2)
• Section I, Getting Started (pp. 1-2, PDF pp. 3-4): keyboard connection through the "DIP" connector at B4, display connection at Molex J2, AC power sources at Molex J1, and a four-step test program
• Section II, Using the System Monitor (pp. 3-7, PDF pp. 5-9): command syntax with worked examples, useful monitor routines, and the commented assembly listing of the monitor PROM at $FF00-$FFFF
• Section III, How to Expand the Apple System (p. 8, PDF p. 10): the 44-pin edge connector, refresh, DMA, and the keyboard and display software interface
• Interfacing circuits: slow ROM, single step for the 6502, address display (PDF p. 12)
• Warranty (PDF p. 13)
• Schematic diagram, drawing 00101, sheets 1-3 of 3 (PDF pp. 14, 15 and 11); sheet 3 includes the power supply

Apple's published specification

Apple-1 Operation Manual, specifications page

Item	Apple's figure
Microprocessor	MOS Technology 6502
Clock frequency	1.023 MHz
Effective cycle frequency	0.960 MHz (including refresh waits)
Video output	Composite positive video, 75 Ω, level adjustable between zero and +5 V p-p
Line rate	15,734 Hz
Frame rate	60.05 Hz
Format	40 characters/line, 24 lines, with automatic scrolling
Display memory	Dynamic shift registers (1K × 7)
Character matrix	5 × 7
RAM	16-pin, 4K dynamic, type 4096 (2104)
On-board RAM capacity	8K bytes (4K supplied)
Power supplies	+5 V at 3 A, ±12 V at 0.5 A, −5 V at 0.5 A
Input power	8-10 V AC (RMS) at 3 A, and 26-28 V AC (RMS) centre-tapped at 1 A
Recommended transformers	Stancor P-8380 or Triad F31-X; Stancor P-8667 or Triad F40-X

What this document settles

The display is not memory-mapped. Apple gives the display memory as "dynamic shift registers (1K x 7)", and software reaches the keyboard and display only through the PIA. At $D010 (KBD data) the high-order bit equals 1. At $D011 (KBD control) the high-order bit indicates "key ready"; reading the key clears the flag and the rising edge of the keyboard strobe sets it. At $D012 (DSP data) the lower seven bits are data output and the high-order bit is a "display ready" input (1 ready, 0 busy); $D013 is the DSP control register.

Four of every 65 clock cycles are given to memory refresh, which is where the 0.960 MHz effective figure comes from. During a refresh cycle ϕ2 is inhibited and the processor is held in ϕ1. Dynamic memory added off-board must take its clock from ϕ0, which is the same as ϕ2 but continues through refresh cycles; PIAs are unaffected because they react to ϕ2 only. For DMA, the solder jumper marked "DMA" on the board must be broken.

Power at the edge connector: only +5 V is regulated. The +12 V, −12 V and −5 V pins carry raw DC of approximately ±14 V, external regulators must be used, and Apple warns: "Exercise great care in the handling of the raw DC, as no short-circuit protection is provided." Address lines are TTL buffered and the data lines can drive ten equivalent capacitive loads (one TTL load and 130 pF) without external buffers. The system is "fully expandable to 65K" through the connector. As supplied, the board draws no more than 1.5 A from the +5 V regulator, which can supply 3 A, so 1.5 A is left for expansion if the transformer is rated for it. The −5 V supply is derived from the regulated −12 V output.

Keyboard: any ASCII keyboard with positive-logic data outputs connects directly; negative-logic outputs need 7404 inverters in the breadboard area. The strobe may be positive or negative, long or short. The B4 connector also carries the RESET and CLEAR SCREEN pushbuttons and supplies +5 V, +12 V and −12 V for the keyboard, and its pin 15 must be tied to +5 V (pin 16) for normal operation. The monitor accepts upper-case A-F and R only.

Pressing RESET enters the monitor, which displays a backslash and drops to the next line. "A backslash alone (cursor remains on same line as backslash) indicates bad page 0 RAM."

Apple's test program exercises the keyboard, display and power supplies together:

1. Press RESET. A backslash should appear and the cursor drop to the next line.
2. Type 0: A9 0 AA 20 EF FF E8 8A 4C 2 0 and RETURN (0 is a zero, not the letter O).
3. Type 0.A and RETURN. The monitor lists the program just entered.
4. Type R and RETURN. The program prints a continuous stream of ASCII characters until RESET is pressed.

Using the monitor

Commands are typed a line at a time, up to 128 characters, and none runs until RETURN is typed. SHIFT-O (backarrow) backspaces and echoes an underline; ESC cancels the line and echoes backslash-return. Addresses use the four least significant hex digits of a group and data values the two least significant.

Monitor command forms (Apple's examples)

User types	Effect
4F	Opens (displays) location $004F
.5A	Displays from the last opened location to $005A
4F.5A	Displays a block in one command
4F 52 56	Displays several single locations; a blank or comma is a delimiter, and a string of delimiters acts as one
4F.52 56 58.5A	Displays several blocks at once
30: A0	Deposits $A0 at $0030
: A1 A2 A3	Deposits into successive locations after the last deposit
10F0 R	Runs the program at $10F0
R	Runs at the most recently examined location

Routines a user program can call: GETLINE at $FF1F (monitor entry), ECHO at $FFEF (prints the ASCII character in A, A not disturbed), PRBYTE at $FFDC (prints A as two hex digits) and PRHEX at $FFE5 (prints the low four bits of A as one hex digit). Locations $0024-$002B are the monitor's index pointers and $0200-$027F its input buffer; neither may be used by a program while the monitor is in use.

What this manual does not contain

It has no parts list, no board layout or component placement drawing, and no troubleshooting procedure beyond the test program and the page-zero RAM indication. Component values have to be read from the schematic sheets. The cassette interface and BASIC had their own manuals.

Pages that cite this document

• Apple I: specifications, test program, monitor behaviour, edge-connector power

Download: Apple-1 Operation Manual 1976.pdf

Related pages

• Apple I
• Apple II Schematics
• Apple II Reference Manual