Franklin Ace 2000
Below: The Franklin Ace 2100 with monochrome monitor
The Franklin Ace 2000 is a clone of the Apple IIe computer. Franklin produced three different models:
- Ace 2000 - No internal floppy drives
- Ace 2100 - Single internal floppy drive
- Ace 2200 - Two internal floppy drives
The Franklin Ace 2000 series is not just a copy of the Apple IIe, but has some improvements. The computer has a separate keyboard, something the Apple II series did not have. There is also the option for an RGB interface card, so a user could connect a high quality RGB monitor. This would improve the image quality over the use of the composite video port of the Apple series.
Franklin settled the lawsuit with Apple over patent infringement in 1984 and for the Ace 2000 series, Franklin produced a legal version of the BIOS and also created it's own operating system: Franklin DOS 2. Both were compatible with Apple.
Franklin DOS (Apple DOS clone)
Functionally, Franklin DOS 2 mirrored Apple DOS at the command level. Users could issue familiar commands like LOAD, SAVE, RUN, or CATALOG exactly as they would on an Apple II running DOS 3.3. The file system also adopted the same 35-track, 16-sector disk layout, which meant disks created on one system could generally be read or written on the other. From the standpoint of a typical BASIC programmer, Franklin DOS 2 appeared to work seamlessly alongside AppleSoft BASIC in ROM.
However, Franklin DOS 2 was not an exact clone under the hood. Certain programs that relied on the internal structure of Apple DOS could fail when run under Franklin’s variant. This limited its usefulness once software libraries began to take advantage of Apple DOS internals for copy protection or direct disk access. The incompatibility issues, although subtle, meant that Franklin’s operating system could not achieve universal acceptance among Apple II software publishers or users.
As a result, Franklin DOS 2 quickly faded into the background. Most ACE owners simply replaced it with Apple DOS 3.3, which was the true standard in the Apple II world, and later with ProDOS once that became widespread. Franklin’s experiment with its own DOS illustrates both the company’s early attempt to skirt Apple’s intellectual property and the reality that in the microcomputer market of the early 1980s, software compatibility mattered more than proprietary differentiation.
CPU - The Motorola 6502
The 6502 is an 8-bit MicroProcessor designed by MOS Technology. The team was led by Chuck Peddle and had also worked on the Motorola 6800. The 6502 is a simplified, but faster and cheaper design than the 6800.
The 6502 was introduced in 1975 and was the cheapest microprocessor on the market. Together with the Zilog Z80, the 6502 helped start the home computer revolution of the 1980s. The 6502 was used in a wide range of devices: the Atari 2600, the 8-bit Atari home computers, the Apple II, the Nintendo Entertainment System, the Commodore 64, the BBC Micro and many others. All used the 6502 or a variation of it.
The 6502 is a 1MHz design, while the 6502A is designed for 2MHz. The 6502A is 100% compatible with the original 6502.
Commodore soon bought MOS Technology, but conitnued to sell the microprocessor to competitors and licensed the design to other manufacturers.
Source: WikiPedia - MOS Technology 6502The 650x Instruction Set
| Mnemonic | Operation | Description |
|---|---|---|
| ADC | Add with Carry | Adds a memory location and the carry bit to the accumulator. |
| AND | Logical AND | Performs a logical AND between memory and the accumulator. |
| ASL | Arithmetic Shift Left | Shifts all bits one position to the left (in memory or accumulator). |
| BCC | Branch on Carry Clear | Branches to a new address if the carry flag is clear (0). |
| BCS | Branch on Carry Set | Branches to a new address if the carry flag is set (1). |
| BEQ | Branch on Equal (Zero Set) | Branches to a new address if the zero flag is set (1). |
| BIT | Bit Test | Tests bits in memory with the accumulator without modifying the accumulator. |
| BMI | Branch on Minus | Branches to a new address if the negative flag is set (1). |
| BNE | Branch on Not Equal | Branches to a new address if the zero flag is clear (0). |
| BPL | Branch on Plus | Branches to a new address if the negative flag is clear (0). |
| BRK | Force Break | Forces an interrupt request and pushes status and PC to the stack. |
| BVC | Branch on Overflow Clear | Branches to a new address if the overflow flag is clear (0). |
| BVS | Branch on Overflow Set | Branches to a new address if the overflow flag is set (1). |
| CLC | Clear Carry Flag | Clears the processor carry flag. |
| CLD | Clear Decimal Mode | Clears the processor decimal mode flag. |
| CLI | Clear Interrupt Disable | Clears the interrupt disable flag, allowing maskable interrupts. |
| CLV | Clear Overflow Flag | Clears the processor overflow flag. |
| CMP | Compare Accumulator | Compares the contents of a memory location with the accumulator. |
| CPX | Compare X Register | Compares the contents of a memory location with the X register. |
| CPY | Compare Y Register | Compares the contents of a memory location with the Y register. |
| DEC | Decrement Memory | Subtracts one from the value held at a specified memory location. |
| DEX | Decrement X Register | Subtracts one from the X register. |
| DEY | Decrement Y Register | Subtracts one from the Y register. |
| EOR | Exclusive OR | Performs a logical Exclusive OR between memory and the accumulator. |
| INC | Increment Memory | Adds one to the value held at a specified memory location. |
| INX | Increment X Register | Adds one to the X register. |
| INY | Increment Y Register | Adds one to the Y register. |
| JMP | Jump | Sets the program counter to a new address. |
| JSR | Jump to Subroutine | Pushes the return address to the stack and jumps to a new address. |
| LDA | Load Accumulator | Loads a byte of memory into the accumulator. |
| LDX | Load X Register | Loads a byte of memory into the X register. |
| LDY | Load Y Register | Loads a byte of memory into the Y register. |
| LSR | Logical Shift Right | Shifts all bits one position to the right (in memory or accumulator). |
| NOP | No Operation | Performs no operation, consuming 2 machine cycles. |
| ORA | Logical Inclusive OR | Performs a logical OR between memory and the accumulator. |
| PHA | Push Accumulator | Pushes a copy of the accumulator onto the stack. |
| PHP | Push Processor Status | Pushes a copy of the status flags onto the stack. |
| PLA | Pull Accumulator | Pulls a byte from the stack into the accumulator. |
| PLP | Pull Processor Status | Pulls a byte from the stack into the processor status flags. |
| ROL | Rotate Left | Rotates all bits one position left through the carry flag. |
| ROR | Rotate Right | Rotates all bits one position right through the carry flag. |
| RTI | Return from Interrupt | Pulls the processor flags and program counter from the stack. |
| RTS | Return from Subroutine | Pulls the program counter from the stack and resumes execution. |
| SBC | Subtract with Carry | Subtracts memory and the inverse of the carry bit from the accumulator. |
| SEC | Set Carry Flag | Sets the processor carry flag. |
| SED | Set Decimal Flag | Sets the processor decimal mode flag. |
| SEI | Set Interrupt Disable | Sets the interrupt disable flag, preventing maskable interrupts. |
| STA | Store Accumulator | Stores the contents of the accumulator in memory. |
| STX | Store X Register | Stores the contents of the X register in memory. |
| STY | Store Y Register | Stores the contents of the Y register in memory. |
| TAX | Transfer Accumulator to X | Copies the current value of the accumulator into the X register. |
| TAY | Transfer Accumulator to Y | Copies the current value of the accumulator into the Y register. |
| TSX | Transfer Stack Pointer to X | Copies the current value of the stack pointer into the X register. |
| TXA | Transfer X to Accumulator | Copies the current value of the X register into the accumulator. |
| TXS | Transfer X to Stack Pointer | Copies the current value of the X register into the stack pointer. |
| TYA | Transfer Y to Accumulator | Copies the current value of the Y register into the accumulator. |
RAM max: 576kB
560x192